https://github.com/j50n/deno-dijkstras-algorithm
A fast and memory-efficient implementation of Dijkstra's shortest-path algorithm for Deno.
https://github.com/j50n/deno-dijkstras-algorithm
algorithm deno dijkstra path shortest
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A fast and memory-efficient implementation of Dijkstra's shortest-path algorithm for Deno.
- Host: GitHub
- URL: https://github.com/j50n/deno-dijkstras-algorithm
- Owner: j50n
- License: mit
- Created: 2021-12-27T02:48:41.000Z (almost 4 years ago)
- Default Branch: main
- Last Pushed: 2022-01-25T05:01:23.000Z (almost 4 years ago)
- Last Synced: 2025-09-09T09:11:16.719Z (2 months ago)
- Topics: algorithm, deno, dijkstra, path, shortest
- Language: TypeScript
- Homepage:
- Size: 33.2 KB
- Stars: 1
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# Dijkstra's Shortest Path Algorithm
A fast and memory-efficient implementation of Dijkstra's shortest-path algorithm
for Deno.
This implementation of Dijkstra'a algorithm is able to process large in-memory
graphs. It will perform reasonably well even with millions of edges. The
performance is `O(n*log(n))`, where `n` is proportional to the number of nodes
plus the number of edges in the graph. The use of integers to represent nodes in
the graph is intentional and actually one of the keys to its performance and
scalability.
This code was adapted to Typescript from
[A Walkthrough of Dijkstra's Algorithm (In JavaScript!)](https://medium.com/@adriennetjohnson/a-walkthrough-of-dijkstras-algorithm-in-javascript-e94b74192026)
on Medium. This implemetation was originally part of
[BlackholeSuns](https://github.com/j50n/blackholesuns), an open source project
that allowed thousands of No Man's Sky players to navigate the galaxy using
mapped black holes. This version is cleaned up a bit and includes a few bug
fixes and more tests than the original. See also
[Dijkstra's algorithm](https://en.wikipedia.org/wiki/Dijkstra%27s_algorithm) on
Wikipedia.
# Documentation
```sh
deno doc --reload https://deno.land/x/dijkstras_algorithm/dijkstra.ts
```
# Run Tests
```sh
deno test --reload
```
# Usage Hints
Dijkstra's algorithm calculates the shortest _paths_ from the start node to
_all_ other nodes in the graph. All of them. In other words, it isn't just
calculating one path at a time. This can let you cheaply do things like find the
20 closest nodes from a particular node in the graph, for example.
One you have loaded a graph definition into a solver, you can clone it. You can
then add nodes to the cloned graph. Loading a large graph over and over takes
time, and depending on overhead, this can be even slower than calculating the
shortest paths. This type of reuse lets you get super-fast results.
# Example
This example recreates the example from the article referenced earlier. The
nodes are mapped to integers from `0` to `n-1`. The names and weights are taken
from
[A Walkthrough of Dijkstra's Algorithm (In JavaScript!)](https://medium.com/@adriennetjohnson/a-walkthrough-of-dijkstras-algorithm-in-javascript-e94b74192026).
```ts
const FULLSTACK = 0;
const DIGINN = 1;
const DUBLINER = 2;
const STARBUCKS = 3;
const CAFEGRUMPY = 4;
const INSOMNIACOOKIES = 5;
const cafes = DijkstraShortestPathSolver.init(6);
cafes.addBidirEdge(DIGINN, FULLSTACK, 7);
cafes.addBidirEdge(FULLSTACK, STARBUCKS, 6);
cafes.addBidirEdge(DIGINN, DUBLINER, 4);
cafes.addBidirEdge(FULLSTACK, DUBLINER, 2);
cafes.addBidirEdge(DUBLINER, STARBUCKS, 3);
cafes.addBidirEdge(DIGINN, CAFEGRUMPY, 9);
cafes.addBidirEdge(CAFEGRUMPY, INSOMNIACOOKIES, 5);
cafes.addBidirEdge(DUBLINER, INSOMNIACOOKIES, 7);
cafes.addBidirEdge(STARBUCKS, INSOMNIACOOKIES, 6);
assertEquals(
cafes.calculateFor(FULLSTACK).shortestPathTo(CAFEGRUMPY),
[FULLSTACK, DUBLINER, INSOMNIACOOKIES, CAFEGRUMPY],
);
assertEquals(
cafes.calculateFor(FULLSTACK).weightOfPathTo(CAFEGRUMPY),
14,
);
```